Immunology Basics Quiz

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Questions and Answers

What role do cytokines play in the immune system?

Cytokines act as molecular messengers that stimulate blood cell production, aid in tissue development, and regulate the immune system.

How does the complement system contribute to direct killing in the immune response?

The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens, leading to the direct lysis of microbial cells.

What is the significance of specificity and memory in vaccination?

Specificity ensures that the immune system targets specific pathogens, while memory allows for a quicker and stronger response upon subsequent exposures to the same pathogen.

Describe the basic principle of the ELISA technique.

ELISA detects antigens in biological samples by using a capture antibody to immobilize the antigen, which is then recognized by a detection antibody. Signup and view all the answers

What is a biosensor and its function in biological applications?

A biosensor is a device that converts biological phenomena into a measurable signal. Signup and view all the answers

What is the primary function of the thymus in the development of T cells?

The thymus is responsible for educating lymphocytes, which become mature T cells. Signup and view all the answers

Which organ is primarily responsible for the production of complement system proteins?

The liver produces proteins of the complement system. Signup and view all the answers

How do lymph nodes contribute to the immune response?

Lymph nodes congregate B cells and T cells to communicate and respond to infections. Signup and view all the answers

From what type of stem cell do all immune system cells originate?

All immune system cells originate from hematopoietic stem cells. Signup and view all the answers

What is the role of the spleen in the immune system?

The spleen filters the blood and provides a site for immune cells to interact with pathogens. Signup and view all the answers

What distinguishes innate immunity from adaptive immunity?

Innate immunity is a first line of defense that recognizes conserved patterns of pathogens, while adaptive immunity targets novel pathogens. Signup and view all the answers

Where do B cells mature in mammals?

B cells mature in the fetal liver and bone marrow. Signup and view all the answers

What is the function of natural killer (NK) cells, and where do they likely originate?

Natural killer cells have cytotoxic activity against infected or cancerous cells and likely originate from the bone marrow. Signup and view all the answers

What are the main pathogens that can contaminate food and water, leading to infections?

Contaminated food can harbor pathogens such as Vibrio cholera, while water can carry viruses like hepatitis. Signup and view all the answers

Describe the difference between direct and indirect contact transmission.

Direct contact transmission occurs through physical interaction, while indirect contact transmission involves fomites that carry pathogens. Signup and view all the answers

What role does the immune system play in defending against pathogens?

The immune system protects the body by using white blood cells to identify and eliminate pathogens. Signup and view all the answers

What is transplacental transmission and provide an example?

Transplacental transmission refers to passing pathogens from mother to fetus via the placenta; an example is rubella virus. Signup and view all the answers

Identify two infections that can be transmitted iatrogenically.

Infections such as HIV/AIDS and Hepatitis B can be transmitted during medical procedures. Signup and view all the answers

What is the primary function of the thymus in the immune system?

The thymus is responsible for the maturation of T cells, which are essential for adaptive immunity. Signup and view all the answers

Explain the significance of lymph in the immune system.

Lymph is a fluid that transports immune-related cells throughout the body to areas needing defense. Signup and view all the answers

How can ingestion lead to intestinal infections? Provide an example.

Ingestion of food or drink contaminated with pathogens can cause intestinal infections, such as cholera. Signup and view all the answers

What constitutes an infection in a host organism?

An infection is the invasion of a host’s bodily tissues by pathogens, their multiplication, and the host's reaction against them. Signup and view all the answers

What are the six links in the chain of infection?

The six links include: the infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host. Signup and view all the answers

Define a healthy carrier and its significance in infection spread.

A healthy carrier harbors a pathogen without having the disease, playing a crucial role in the transmission of the infection to others. Signup and view all the answers

What distinguishes zoonotic diseases from other infections?

Zoonotic diseases are infections transmitted from animals to humans and can be caused by various types of pathogens including bacteria, viruses, and protozoa. Signup and view all the answers

What is the difference between mechanical and biological vectors?

Mechanical vectors carry pathogens on their body surfaces without them multiplying, while biological vectors host pathogens allowing them to multiply within. Signup and view all the answers

What is meant by the term 'chronic carrier'?

A chronic carrier is an individual who harbors a pathogen for several years, sometimes for life, without necessarily showing symptoms. Signup and view all the answers

List one example of a zoonotic disease and its source.

Rabies is an example of a zoonotic disease transmitted from dogs. Signup and view all the answers

What role does soil and water play in the survival of pathogens?

Some pathogens can survive in soil and water for extended periods, serving as reservoirs for potential infections. Signup and view all the answers

What are the two main types of lymphocytes and their primary functions?

The two main types of lymphocytes are B cells, which produce antibodies, and T cells, which directly destroy infected cells. Signup and view all the answers

What is the role of antibodies in the immune system?

Antibodies are proteins produced by the immune system to identify and neutralize antigens, such as bacteria and viruses. Signup and view all the answers

Describe the three broad functions of the complement system.

The complement system enhances inflammation, opsonizes pathogens for clearance, and directly kills target cells by lysis. Signup and view all the answers

What are phagocytes and what is their main function in the immune response?

Phagocytes, such as neutrophils and monocytes, are immune cells that ingest and destroy microbes and cellular debris. Signup and view all the answers

How does inflammation assist the immune response during an infection?

Inflammation concentrates immune cells and products at the infection site through increased blood flow and vessel permeability. Signup and view all the answers

What is opsonization and why is it important for phagocytes?

Opsonization is the process where complement components coat the bacterial surface to enhance recognition by phagocytes. Signup and view all the answers

What are the two types of T cells, and how do they differ in function?

The two types of T cells are Cytotoxic T cells, which directly destroy infected cells, and Helper T cells, which assist in regulating immune responses. Signup and view all the answers

What happens if inflammation becomes prolonged?

Prolonged inflammation can lead to tissue damage and chronic disease due to continuous immune activity at the site. Signup and view all the answers

Study Notes

Infection and Disease

Infection is the invasion of a host organism's bodily tissues by pathogens or infectious agents, their multiplication and the reaction of host tissue against them.
Pathogens include bacteria, viruses, fungi, and parasites.
Pathogenicity refers to the ability of a pathogenic agent to cause disease
Examples of diseases caused by pathogens. Strep throat, staph infections, tuberculosis, food poisoning, tetanus, pneumonia, syphilis, common cold, flu, genital herpes, cold sores, measles, AIDS, genital warts, chicken pox, small pox, ringworm, athlete's foot, tineas, candidiasis, histoplasmosis, mushroom poisoning, malaria, "traveller's diarrhea", giardiasis, and trypanosomiasis ("sleeping sickness").

Chain of Infection

The chain of infection consists of 6 intertwined links that allow for the spread of communicable diseases.
Each step in the chain is needed to effectively spread infections.
Breaking any one of the six links can slow the spread of infectious disease
The 6 links are Susceptible host (elderly, infants, immunocompromised, anyone), Pathogen (bacteria, virus, fungi, parasite), Portal of entry (mouth, nose, eyes, cuts in skin), Mode of transmission (direct contact, indirect contact, vectors), Reservoir (people, animals, soil, food, water), Portal of exit (coughing/sneezing, bodily secretions, feces).

Reservoir

Reservoir refers to any living or non-living thing that harbors a parasite, allowing multiplication and survival
Human cases and carriers are the most common source of infections
Examples include healthy carriers, convalescent carriers, temporary carriers, chronic carriers, and contact carriers

Zoonoses

Zoonotic diseases are infectious diseases transmitted from animals to humans.
Examples of Zoonotic Diseases:
- Bacterial: bovine tuberculosis
- Viral: rabies from dogs
- Protozoal: Toxoplasmosis from cats
- Helminthic: Taeniasis from cattle
- Fungal: dermatophytes from dogs

Insects as Reservoirs

Arthropods, or insects, that transmit infectious diseases are called vectors
Vectors can carry pathogens mechanically (on their wings, legs or body, eg, transmission of typhoid by flies) or biologically (pathogens multiply within the vector, eg., malaria by mosquitoes)
The time required after introducing a pathogen to make the vector infective is called the extrinsic incubation period.

Soil and Water as Reservoirs

Some pathogens linger in the soil for a long time, eg. tetanus and gas gangrene bacteria, histoplasmosis fungus, and parasitic worms
Contamination of water with Vibrio cholera and hepatitis virus can spread infection

Food as a Reservoir

Contaminated food can act as a source of food poisoning, gastroenteritis, diarrhea, and dysentery

Modes of Transmission

Contact:
- Direct contact: physically touching an infected person (syphilis, gonorrhea, herpes simplex type 2, AIDS)
- Indirect contact: indirectly through fomites (inanimate objects)
Airborne:
- Droplet nuclei (1-10 micron diameter): act as aerosols—remain airborne and spread by inhalation (respiratory infections).
Ingestion: Ingesting contaminated food or beverages causing infections like cholera, dysentery, food poisoning,
Inoculation: Pathogens enter through breaks in the skin or mucous membranes, for example, through a bite (rabies virus) or spores (tetanus).
Transplacental: Pathogens transmitted from mother to fetus via the placenta.
Iatrogenic: Infections acquired during medical procedures (AIDS and Hepatitis B).

Immunity

Immune system: The organs and tissues working to maintain proper functioning include the thymus, bone marrow, lymph nodes, lymphatic vessels, spleen, and skin.
White blood cells: Circulate in blood and lymphatic vessels, working as guards against pathogens
Lymphatic system: Carrying lymph fluid (immune-related cells) to areas needing them, similar to blood circulation.
Lymphocytes: White blood cells playing crucial roles in immunity and are of two main types
B cells: Produce antibodies targeting harmful cells.
T cells: Destroy bacteria or virus-infected cells (Cytotoxic T cells) and help other immune cells (Helper T cells)

Major Organs of the Immune System

Liver: Filters blood, producing proteins and combating bacteria.
Bone marrow: Site where immune cells originate.
Tonsils: Lymph tissue collections in the throat.
Lymph nodes: Collection points for B and T cells, allowing cell communication. Crucial in cases of infection.
Spleen: Filters blood, removing old blood cells and pathogens, functioning as a site for immune interactions between cells.
Blood: Contains immune cells and proteins circulating throughout the body.

Origins of Immune System Cells

Immune cells originate from hematopoietic stem cells.
Platelets are fragments of megakaryocytes.
Polymorphonuclear granulocytes and monocytes circulate in blood before migrating to tissues.
B cells mature in the liver or bone marrow, and T cells mature in the thymus.
The large granular lymphocytes (NK) play a role in killing infected cells.

Types of Immunity

Innate Immunity: Ancient defense system, recognizing conserved pathogen patterns (the first line of defense).
Adaptive Immunity: A more recent evolutionary innovation. Recognizes novel pathogens by detecting specific molecules.
Active immunity: Develops when an individual is exposed to a pathogen or gets vaccinated.
Passive immunity: Acquired when receiving antibodies from another source (mother's milk, injections).

How do Antibodies work?

Antigen: Undesirable foreign substance entering the body (e.g., bacteria, viruses).
Antibody: A protein created by the immune system to fight antigens by binding onto them to neutralize or destroy them. Immunoglobulin is another word for antibody.

How does Immune System Work - Particularly?

Complement system: Enhance antibody and phagocytic cell activity.
Opsonization: Complement components coating bacterial surfaces—allowing phagocytes to identify and engulf bacteria.
Direct Killing: Complement activation leads to pores forming on cell surfaces of pathogens, causing cell lysis.
Inflammation: Immune cells concentrating and migrating to infection sites by changes in blood flow and vessel permeability.
Phagocytes (Macrophages, Neutrophils and Monocytes): Circulating and migrating through tissues to destroy microbes and cellular debris.
Cytokines: Proteins produced by cells acting as intercellular messengers, impacting blood cell production, tissue repair, and immune regulation.

Vaccination

Key elements based on specificity and memory.
A weakened pathogen/toxin (toxoid) introduces immunity without causing disease.
The body creates antibodies against the pathogen for future protection.
Primary vaccination, introducing the vaccine for the first time. Second vaccination, causing an enhanced antibody response.

Diagnosis

Methods to identify infections.
Procedures employed by LFIA, ELISA, RT-PCR, RT-LAMP, CRISPR, NTS, and Biosensors.

ELISA (Enzyme-linked Immunosorbent Assay)

Technique for detecting presence of antibodies or antigens in a sample.
Samples are tested for diseases like HIV, Lyme disease, Covid-19.

Biosensor

A device that converts biological phenomena into measurable signals.
Examples include pregnancy tests and glucose monitors.

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Description

Test your knowledge on the immune system's components, including cytokines, the complement system, and the role of various organs. This quiz covers essential concepts such as vaccination specificity, ELISA techniques, and interactions between different immune cells. Perfect for students studying immunology or related fields.